Metal ceramic crowns--a review of tooth preparation.

The metal ceramic crown has become the most popular extra-coronal restoration in the armamentarium of the dentist, certainly within the UK. It combines the aesthetic qualities of porcelain with the strength of cast metal. This review discusses a number of issues relating to these crowns, and considers the principles of tooth preparation and marginal fit. The physical requirements of tooth preparation are considered in terms of shoulder width, emergence profile, shoulder angle and effects on the pulp. It also considers the teaching of metal ceramic crown preparation, the failure of metal ceramic crowns and the influence that preparation quality has on these failures.